Acoustic device



June17,1930. M.P.BONNAT L J ACOUSTIC DEVICE Filed Decu 16, 1927 4 INVENTOR :1 Max Paul Bonnat ATTORNEYS Patented June 17, 1930 UNITED STATES MAX PAUL BONNLT, OF NEW YORK, N. 31., ASSIGNOR E ONE-HALE 0 PETER PMDELI 7 '60. I110, OF NEW YORK, N. Y., A CORPORATIQN OF N YORK ACOUSTIC DEVICE Application died December 1%, 1927. serial ltoiamfict.

invention relates to improvements in acoustic devices, and more particularly to the diaphragm or sound regenerator of a radio loud speaker unit.

Among the radio loud speaker units now upon the market is the cone loud speaker, one form whereof is shown in the patent to Hopkins No. 1,271,529, granted July 2, 1918.

Loud speakers of this type employ the cone no element as the diaphragm. The cone is closed at the apex and is secured at that point to the driving unit. At the point of juncture the cone is invariably reinforced or stififened with one or more metal washers. The body of the to cone possesses the characteristics of a membrane and constitutes a diaphragm for reproducing sound. The apex or point of juncture with the driving unit is not resilient and is consequently not receptive to vibrations and, therefore, constitutes a dead spot which impairs the quality of the sounds emitted by the cone. This tends to impair the acoustical properties of the loud speaker unit.

The objectof this invention is a more citicient form of acoustic device.

\ Another object of this invention is the elimination of distortion.

, In accordance with this invention the acoustic device comprises a diaphragm made in the form of a frustum of a hollow cone, the sound reproducin apparatus being connected to the sma er aperture of the cone.

In the drawings comprising but a single sheet of six figures, the invention is diagrammatically setforth.

Figure 1 is a sectional view. ofone form of the device;

Figure 2 1s a sectional view of one alternative form;

Figure 3 is an enlarged sectional view of some of theparts of the device of Figure 1, showing certain details of construction;

Figur e 4 is an enlarged front .view of some of the parts of Figure 1 looking at .said figure from the right; a 5 is a perspective of one of the dey tails of construction; and

' Figure 6 is a perspective of certain other details of construction.

Like reference characters designate like aluminum has been found to give very satishollow cone. The ends of the body portion parts throughout the several figures of the drawings.

The body 7 defines a fru'sto-conical tubular diaphragm. It may be made of any prei'erred material; parchment, stifi paper, or even very thin metal may be employed, so long as the material used has the characteristic thinness of a membrane.

If the body 7 is made of metal it should be corrugated. Where metal isthus employed iactory results.

The body 7 may be formed from a blank sheet the ends whereof are secured together so that the Whole defines the frustum of a maybe united by means of a suitable cement or glue. When thus united the body 7 presents the appearance shown in Figures 1 and 2. The outer edge 8, which may be either free or clamped as preferred, defines the mouth of a frusto-conical tube and the inner edge 9' defines the throat 11 thereof. A suitable annular reinforcing stri. 10 is secured to the body 7 adjacent the e go 9. This reinforcing strip furnishes additional strength adjacent the throat 11.

If the outer edge 8 is a free edge it is preferably, revcrsely bent as indicated at 12 in Figures 1 and 2. This tends to furnish additional strength to the free edge of the cone and to maintain the body portion 7 tightly stretched.

Means are provided for securing the diaphragm to the driving rod of the sound reproducing apparatus. This means preferably comprises a plurality of rivets-15, a plurality of metal clips 13 of the'character disclosed in Figure 5, each of which is provided with holes as at 14 to permit the insertion of the rivet 15 (Figure 3) and a plurality of metal vibrating strips 16 each provided with a base member 17 having a suitable aperture therein to permit the insertion of a rivet 15.

A clip 13 is placed under the metal strip 16 at the point where it is secured to the inner edge 9, and a light hollow rivet 15 is passed through apertures in the body-portion 7 reinforcing strip 10, clip 13 and base member 17 and the several parts are then 1 riveted securely together. The metal vibrat ing strips 16 ma be made either single or double. In the rawings a suitable double form is shown. When used double the stri s are bent to define two sides of a triangle, t e apex bein aperture or use as herelnafter set forth.

' Whether single or double vibrating strips are used, the apertures 18 are all brought into alignment and the threaded stem 19 of the connecting sleeve 20 is inserted therein and the nut 21 is ti htened upon the threaded stem 19 until the vibrating strips 16 are clamped tightly together.

If an'even number of strips 16 is used the strips are preferably double, as shown in the drawings, but if an odd number of strips is used the may be made singly. The strips 16 should be equally spaced around the inner edge 9, as is best indicated in Figure 4, which illustrates the preferred arrangement to be followed where two double strips 16 are employed.

The driving rod of the sound reproducing apparatus is inserted in the bore 22 of the connecting sleeve 20 and the screw 23 is tightened to unite the driving rod to the connecting sleeve. Any movement of the driving rod is thus transmitted to the body 7 (which constitutes a diaphragm) by way of the vibrating strips 16. As the strips 16 are made of metal they transmit the vlbrations imparted to them more readily and more rapidly than would be the case if the driving rod was secured to a non-metallic medium, as was customary in the prior art.

The inner edge 9 of the frusto-conical tube will be flexible at practically every point throughout its circumference, the only rigid points being those where the vibrating strips 16 are secured.

It will be observed that every part of the body 7 is free to vibrate. This is a great advantage over the cones heretofore used as diaphragms in bud speakers wherein the bod terminated in an apex forming an integra part of the diaphragm and which .apex is always rigid and, therefore, constitutes a dead spot incapable of vibration. The elimination of the apex likewise eliminates rigidity, and this in turn results in the elimination of muflling, thereby avoiding distortion.

I It, therefore, appears that applicants body portion 7 which defines a frusto-conical tube (the smaller opening 11 thereof constituting the throat and the larger opening the mouth),

is a diaphragm which will respond to and amplify the vibrations set up in the vibrating strips 16 by the driving rod of the sound reproducing apparatus.

The sound reproducing apparatus may be of any preferred form, it being understood that the driving rod of the sound reproducflattened and provided with an ing apparatus is secured in any suitable manner to the connecting sleeve 20.

What is claimed is:

1. An acoustical device comprising a diaphragm, said diaphragm defining a frustoconical tube, the smaller opening in the tube defining the throat of the acoustical device, a connecting sleeve secured to the sound reproducing apparatus, and a series of spaced rods defining vibrating members secured to the sleeve and to the periphery of the throat.

2. An acoustic device, comprising a conical truncated dia hragm, a connecting sleeve secured the iaphragm, and spaced rods defining vlbrating mem ers secured to the sleeve and to the periphery of the diaphragm, said rods being positioned in diverging relation to form a connecting spider.

3. An acoustic device, comprising a conical, truncated dia hragm, a connecting sleeve secured to the diaphragm, spaced rods defining vibratin members secured to the sleeve and to the periphery of the diaphragm, said rods being positioned in diver 'ng relation to form a connecting-spider, and means joining the converging ends of saidrods.

4. An acoustic device, comprising a conical, truncated diaphragm, a connecting sleeve secured .to the diaphragm, spaced rods defining vibrating members secured to the sleeve and to the periphery of the diaphragm, said rods-being positioned in diverging relationto form a. connecting spider, and means oining the converging ends of said rods, said means acting as connecting means for an actuating unit.

5 An acoustic device, comprising a frustocon cal diaphragm, and an actuatlng means oining the smaller end of said dia hragm with an actuating unit, said. means ihrming a spider.

6. An acoustic device, conical diaphragm, and an actuating means ]O 1I1ing the smaller end of said dia hragm wlth an actuating unit, said means ormlng a spider including diverging fin rs.

7. An acoustic device, comprising a frustoconlcal diaphragm, and an actuating means o 1n1ng the smaller end of' said dia hragm with an actuating unit,-said means orming a spider including diverging. fin ers, said fin ers beingqarranged in conlcal ormation.

igned at ew York, in the county of New York and State of New York, this 13th day of December, 1927.

MAX PAUL BON NAT. 

